U.S. patent application number 11/379108 was filed with the patent office on 2006-10-19 for sensor assembly for determining the temperature state in an area of a heating surface.
Invention is credited to Christian Auradnik, JOSEF REITHOFER.
Application Number | 20060231546 11/379108 |
Document ID | / |
Family ID | 35070933 |
Filed Date | 2006-10-19 |
United States Patent
Application |
20060231546 |
Kind Code |
A1 |
REITHOFER; JOSEF ; et
al. |
October 19, 2006 |
SENSOR ASSEMBLY FOR DETERMINING THE TEMPERATURE STATE IN AN AREA OF
A HEATING SURFACE
Abstract
A sensor assembly is disclosed for determining the temperature
state in an area of a heating surface heated by a heat source and
disposed between the heat source and the heating surface in
parallel relationship to the heating surface. The sensor assembly
includes a first sensor having a carrier and a
temperature-dependent resistor web which is attached to the carrier
and confronts the heating surface and which is electrically
contacted at a contact zone outside a temperature-measuring zone,
and a second sensor having a carrier and a temperature-dependent
resistor web which is attached to the carrier and electrically
contacted at a contact zone outside the temperature-measuring zone
and which confronts the heat source.
Inventors: |
REITHOFER; JOSEF;
(Wolfpassing, AT) ; Auradnik; Christian;
(Klosterneuburg, AT) |
Correspondence
Address: |
HENRY M FEIEREISEN, LLC
350 FIFTH AVENUE
SUITE 4714
NEW YORK
NY
10118
US
|
Family ID: |
35070933 |
Appl. No.: |
11/379108 |
Filed: |
April 18, 2006 |
Current U.S.
Class: |
219/448.19 |
Current CPC
Class: |
D06M 15/3562 20130101;
G01K 1/14 20130101; H05B 3/748 20130101; D06M 2200/00 20130101 |
Class at
Publication: |
219/448.19 |
International
Class: |
H05B 3/68 20060101
H05B003/68 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 19, 2005 |
AT |
GM 241/2005 |
Claims
1. A sensor assembly for determining the temperature state in an
area of a heating surface heated by a heat source and disposed
between the heat source and the heating surface in parallel
relationship to the heating surface, said sensor assembly
comprising: a first sensor having a carrier and a
temperature-dependent resistor web which is attached to the carrier
and confronts the heating surface and which is electrically
contacted at a contact zone outside a temperature-measuring zone;
and a second sensor having a carrier and a temperature-dependent
resistor web which is attached to the carrier and electrically
contacted at a contact zone outside the temperature-measuring zone
and which confronts the heat source.
2. The sensor assembly of claim 1, wherein the heating surface is a
glass ceramic hot plate.
3. The sensor assembly of claim 1, wherein the carrier of the first
sensor is made of ceramic.
4. The sensor assembly of claim 1, wherein the carrier of the
second sensor is made of ceramic.
5. The sensor assembly of claim 1, wherein at least one of the
resistor web of the first sensor and the resistor web of the second
sensor is shaped in the form of a meander.
6. The sensor assembly of claim 1, wherein at least one of the
resistor web of the first sensor and the resistor web of the second
sensor is made through a thick-film technique.
7. The sensor assembly of claim 1, wherein the first sensor and the
second sensor are substantially identical in construction.
8. The sensor assembly of claim 1, wherein the second sensor is of
a greater size than the first sensor.
9. The sensor assembly of claim 1, wherein the second sensor is
constructed to absorb radiation.
10. The sensor assembly of claim 1, wherein at least one of the
resistor web of the first sensor and the resistor web of the second
sensor is greater in cross section in a transition zone than in an
area of the temperature-measuring zone.
11. The sensor assembly of claim 1, wherein at least one of the
resistor web of the first sensor and the resistor web of the second
sensor is twice in cross section in a transition zone than in an
area of the temperature-measuring zone.
12. The sensor assembly of claim 1, constructed to have a
configuration tapering toward a free end distal to the contact zone
for improving mechanical stability.
13. The sensor assembly of claim 1, constructed to have a wide zone
in an area of the contact zone, and a transition of curved
configuration to a remaining narrow zone.
14. The sensor assembly of claim 1, wherein the transition is
curved concavely.
15. The sensor assembly of claim 1, wherein at least one of the
resistor web of the first sensor and the resistor web of the second
sensor has a length of at least 200 mm in the temperature-measuring
zone.
16. The sensor assembly of claim 1, further comprising a contact
piece of elastically yielding material for establishing contact of
at least one of the resistor web of the first sensor and the
resistor web of the second sensor in the contact zone, said contact
piece being connected to the carrier of the least one of the
resistor web of the first sensor and the resistor web of the second
sensor.
17. The sensor assembly of claim 16, wherein the contact piece is
riveted to the carrier.
18. The sensor assembly of claim 1, further comprising a closed
thermally conductive passivation layer for insulating at least one
of the resistor web of the first sensor and the resistor web of the
second sensor.
19. The sensor assembly of claim 1, further comprising a retention
element between the first sensor and the second sensor.
20. The sensor assembly of claim 19, wherein the retention element
has the shape of a bracket or a trough.
21. The sensor assembly of claim 20, further comprising insulating
material disposed in a space defined by the bracket or the
trough.
22. The sensor assembly of claim 19, wherein the retention element
has the shape of a trough having a bottom formed with reinforcing
grooves to define pockets for providing insulation.
23. The sensor assembly of claim 19, further comprising a spring
tongue attached to at least one of the second sensor and retention
element and supported by the first sensor.
24. The sensor assembly of claim 19, wherein the second sensor has
at least an area for connection to the retention element.
25. The sensor assembly of claim 19, wherein the retention element
has a receptacle for accommodating the first sensor.
26. The sensor assembly of claim 19, further comprising an
elastically yielding connection element for connecting the first
sensor in the area of the contact zone to at least one of the
second sensor and retention element.
27. The sensor assembly of claim 26, wherein the connection element
is a spring.
28. The sensor assembly of claim 26, wherein the connection element
is a metal spring.
29. The sensor assembly of claim 26, wherein the connection element
is a U-shaped spring.
30. The sensor assembly of claim 26, wherein the connection element
is a Z-shaped spring.
31. The sensor assembly of claim 26, wherein the connection element
is connected thermally to at least one of the first sensor, second
sensor, and retention element.
32. The sensor assembly of claim 31, further comprising fastening
means including bolts and/or rivets for connecting the connection
element to at least one of the first sensor, second sensor, and
retention element.
33. The sensor assembly of claim 26, wherein the retention element
has a receptacle for accommodating the first sensor, said first
sensor having a step-shaped configuration in an area of the contact
zone to define a recessed zone which extends at a lower level than
the connection element, with the resistor web of the first sensor
extending in substantial parallel relationship to the resistor web
of the second sensor, when the first sensor is disposed completely
in the receptacle of the retention element.
34. The sensor assembly of claim 33, wherein the carrier of the
first sensor is made of several parts in an area of the recessed
zone.
35. The sensor assembly of claim 19, further comprising a
substantially angular restraining bracket connected to at least one
of the second sensor and retention element.
36. The sensor assembly of claim 19, further comprising a
substantially angular bracket riveted or bolted to at least one of
the second sensor and retention element.
37. The sensor assembly of claim 1, wherein the first sensor rests
flatly on the heating surface in operative position and defines a
wedge-shaped gap in combination with heads of rivets.
38. The sensor assembly of claim 35, wherein the restraining
bracket has a receptacle for accommodating the second sensor.
39. The sensor assembly of claim 35, wherein the restraining
bracket has a bay for insertion of the second sensor.
40. The sensor assembly of claim 35, wherein in operative position
the restraining bracket has a vertical surface formed with a
vertical oblong hole for installation and adjustment.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the priority of Austrian Patent
Application, Serial No. GM 241/2005, filed Apr. 19, 2005, pursuant
to 35 U.S.C. 119(a)-(d), the content of which is incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates, in general, to a sensor
assembly for determining the temperature state in an area of a
heating surface.
[0003] Nothing in the following discussion of the state of the art
is to be construed as an admission of prior art.
[0004] In typical electric stoves, particularly those having a
ceramic cooktop, an electromechanical protective temperature
limiter is provided per heater to limit it to the maximum
temperature. If the cooking platform is controlled using an
electronic system, a substitution of the mechanical temperature
limiter by electronic temperature sensors is possible, since the
necessary circuit breaker (relay) is already provided. In the
electronic control units used, a sensor is frequently also
positioned in the region of the electronics of an electric
stove.
[0005] Conventional temperature sensors are insufficient to provide
a true representation of the temperature distribution underneath
the heating surface. As a result, the electronic control circuits
receive only incomplete data so that the heating surface can only
controlled poorly, causing excessive amount of energy to be
unnecessarily converted into heat.
[0006] It would therefore be desirable and advantageous to provide
an improved sensor assembly to obviate prior art shortcomings and
to allow precise temperature control of a heating surface to
thereby enhance efficiency and lower energy consumption.
SUMMARY OF THE INVENTION
[0007] According to one aspect of the present invention, a sensor
assembly for determining the temperature state in an area of a
heating surface heated by a heat source and disposed between the
heat source and the heating surface in parallel relationship to the
heating surface, includes a first sensor having a carrier and a
temperature-dependent resistor web which is attached to the carrier
and confronts the heating surface and which is electrically
contacted at a contact zone outside a temperature-measuring zone,
and a second sensor having a carrier and a temperature-dependent
resistor web which is attached to the carrier and electrically
contacted at a contact zone outside the temperature-measuring zone
and which confronts the heat source.
[0008] A sensor assembly according to the present invention enables
a temperature measurement in the entire heating space so that prior
art problems are resolved and an added safety feature is realized
as far as temperature control is concerned in the event one sensor
malfunctions or is incorrectly controlled. Moreover, the
temperature measurement is more accurate. By knowing the
temperature of the heat source, the temperature of the heating
surface can be ascertained before it reaches the desired level so
that the temperature or the heat source can be fine-tuned. As a
result, the desired temperature of the heating surface can be
reached more quickly or energy can be saved when maintaining the
heating surface at the desired temperature because the heating
surface temperature and the heat source temperature can be suited
to one another in an optimum manner. The temperature sensors used
for a sensor assembly according to the present invention can be
manufactured cheaply so that the addition of a second temperature
sensor is of no financial consequence. Operating safety and
efficiency of the cooking platform is much enhanced as both the
heating surface temperature and the heat source temperature can be
ascertained at any time and determination of a characteristic
temperature graph inside the heating unit is possible using a
processor. This in turn can be used for calibrating and
self-adjusting the heating unit.
[0009] According to another feature of the present invention, the
heating surface may be a glass ceramic hot plate, and the carrier
of the first and second sensors may be made of ceramic.
[0010] According to another feature of the present invention, the
resistor web of the first sensor and/or the resistor web of the
second sensor may be shaped in the form of a meander. Suitably, the
resistor web of the first sensor and/or the resistor web of the
second sensor may be made through a thick-film technique. In this
way, the resistance pattern can be best suited in an easy manner to
the application at hand.
[0011] According to another feature of the present invention, the
first sensor and the second sensor may be made substantially
identical in construction. Manufacture and storage are thus simple
and cost-effective. As an alternative, the second sensor may be
sized greater than the first sensor. In this way, the second sensor
is able to protect the first sensor from exposure to heat radiating
from the heat source so that the temperature measurement by the
first sensor becomes more accurate. In addition, the second sensor
may be constructed to absorb radiation to further shield the first
sensor from the heat source.
[0012] According to another feature of the present invention, the
resistor web of the first sensor and/or the resistor web of the
second sensor may be greater, e.g. twice, in cross section in a
transition zone than in an area of the temperature-measuring zone.
As a result, the electric resistance per length of the resistor web
is significantly reduced in this area so that the temperature
measurement in this area is hardly affected.
[0013] According to another feature of the present invention, the
sensor assembly may be constructed to have a configuration tapering
toward a free end distal to the contact zone for improving
mechanical stability. Thus, the carrier can be constructed light
and in a material saving manner while still exhibiting sufficient
mechanical stability, whereby shading of the heating coil in
particular on the contact-distal end can be kept to a minimum by
the carrier or can be selected great and dimensioned specific to a
local in order to set the desired temperature gradient on the
cooking platform and heating surface.
[0014] According to another feature of the present invention, the
sensor assembly may be constructed to have a wide zone in an area
of the contact zone, and a transition curved to a remaining narrow
zone. Suitably, the transition is concave. In this way, material
can be utilized efficiently without adversely affecting
stability.
[0015] According to another feature of the present invention, the
resistor web of the first sensor and/or the resistor web of the
second sensor may have a length of at least 200 mm in the
temperature-measuring zone. As a result, temperature is absorbed
across an area of great spatial range, thereby further enhancing
the accuracy of measurement.
[0016] According to another feature of the present invention, a
contact piece of elastically yielding material may be provided for
establishing contact of the resistor web of the first sensor and/or
the resistor web of the second sensor in the contact zone, with the
contact piece being connected, e.g. riveted, to the carrier of the
resistor web of the first sensor and/or the resistor web of the
second sensor. Sufficient contacting is hereby realized, even when
exposed to frequent changing temperature stress.
[0017] According to another feature of the present invention, a
closed thermally conductive passivation layer may be provided for
insulating the resistor web of the first sensor and/or the resistor
web of the second sensor. The resistor web is thus protected
reliably from chemical impacts and retains its thermoelectric
characteristic for a longer period so that a drift over time of the
measuring range is minimized. In this way, rivets may also be
shielded or covered.
[0018] According to another feature of the present invention, a
retention element may be provided between the first sensor and the
second sensor. In this way, a defined distance can be maintained.
The provision of such a retention element insulates also the first
sensor. The retention element may be implemented in the form of a
bracket or may have the shape of a trough. Suitably, the bracket or
the trough defines hereby a space for receiving insulating
material. As a result, the retention element is simple in structure
and stiff and has space for insulation material. As an alternative,
the retention element may have a trough bottom which is formed with
reinforcing grooves to define pockets for providing insulation.
This effectively improves the insulation in a simple manner.
[0019] According to another feature of the present invention, a
spring tongue may be attached to the second sensor and/or retention
element and supported by the first sensor. As a result, the first
sensor is precisely placed on the heating surface.
[0020] According to another feature of the present invention, the
second sensor may, at least regionally, be connected to the
retention element, and/or the retention element may have a
receptacle for accommodating the first sensor. Thus, the second
sensor can be supported precisely while being supported by the
planar disposition of the first sensor. The disposition in the
receptacle effects also a sealing of a void in the receptacle so
that trapped air in the void can provide insulation.
[0021] According to another feature of the present invention, an
elastically yielding connection element may be provided for
connecting the first sensor, in particular the carrier thereof, in
the area of the contact zone to the second sensor and/or retention
element. Examples of a connection element include a spring, e.g. a
metal spring, U-shaped spring, or Z-shaped spring. In this way, the
first sensor can be precisely placed upon the heating surface.
Suitably, the connection element may be connected thermally to the
first sensor, second sensor, and/or retention element, in
particular by using bolts and/or rivets. This ensures a secure
connection of the elastically yielding connection element in the
space between heating surface and heat source, even when subjected
consistently to high temperatures.
[0022] According to another feature of the present invention, the
retention element may have a receptacle for accommodating the first
sensor, with the first sensor having a step-shaped configuration in
an area of the contact zone to define a recessed zone which extends
at a lower level than the connection element, wherein the resistor
web of the first sensor extends in substantial parallel
relationship to the resistor web of the second sensor, when the
first sensor is disposed completely in the receptacle of the
retention element. In this way, the first sensor can be securely
placed flatly on the heating surface, even when using bolts and
rivets because the heads of the bolts or rivets are prevented from
bearing upon the heating surface. Suitably, the carrier of the
first sensor may be made of several parts in an area of the
recessed zone. This results in a particularly simple configuration
of the carrier.
[0023] According to another feature of the present invention, a
substantially angular restraining bracket may be connected, e.g.
bolted or riveted, to the second sensor and/or retention element.
This allows easy and flexible attachment to the surroundings or
heating space or oven.
[0024] According to another feature of the present invention, the
first sensor rests flatly on the heating surface in operative
position and defines a wedge-shaped gap in combination with heads
of rivets. As a consequence, the first sensor is coupled directly
to the heating surface and the temperature indication is
accurate.
[0025] According to another feature of the present invention, the
restraining bracket may have a receptacle for accommodating the
second sensor. In particular, the restraining bracket may have a
bay for insertion of the second sensor.
[0026] According to another feature of the present invention, the
restraining bracket in operative position may have a vertical
surface formed with a vertical oblong hole for installation and
adjustment. This allows easy assembly and adjustment of the sensor
assembly.
BRIEF DESCRIPTION OF THE DRAWING
[0027] Other features and advantages of the present invention will
be more readily apparent upon reading the following description of
currently preferred exemplified embodiments of the invention with
reference to the accompanying drawing, in which:
[0028] FIG. 1 is an axonometric view of a first embodiment of a
sensor assembly according to the present invention;
[0029] FIG. 2 is a side view of the sensor assembly;
[0030] FIG. 3 is a cross sectional view of the sensor assembly;
[0031] FIG. 4 is an axonometric view of a second embodiment of a
sensor assembly according to the present invention;
[0032] FIG. 5 is a side view of the sensor assembly of FIG. 4;
[0033] FIG. 6 is a cross sectional view of the sensor assembly of
FIG. 4;
[0034] FIG. 7 is an axonometric view of a third embodiment of a
sensor assembly according to the present invention;
[0035] FIG. 8 is a side view of the sensor assembly of FIG. 7;
[0036] FIG. 9 is a cross sectional view of the sensor assembly of
FIG. 7;
[0037] FIG. 10 is an axonometric view of a fourth embodiment of a
sensor assembly according to the present invention;
[0038] FIG. 11 is a side view of the sensor assembly of FIG.
10;
[0039] FIG. 12 is a cross sectional view of the sensor assembly of
FIG. 10;
[0040] FIG. 13 is a side view of a fifth embodiment of a sensor
assembly according to the present invention;
[0041] FIG. 14 is a cross sectional view of the sensor assembly of
FIG. 13;
[0042] FIG. 15 is an axonometric view of a sixth embodiment of a
sensor assembly according to the present invention;
[0043] FIG. 16 is a side view of the sensor assembly of FIG.
15;
[0044] FIG. 17 is a cross sectional view of the sensor assembly of
FIG. 15;
[0045] FIG. 18 is a cross sectional view of a seventh embodiment of
a sensor assembly according to the present invention;
[0046] FIG. 19 is an axonometric view of sensor assembly according
to the present invention in combination with a heat source;
[0047] FIG. 20 is a cross sectional view of the sensor assembly of
FIG. 19;
[0048] FIG. 21 is a top view of a first sensor of a sensor assembly
according to the present invention;
[0049] FIG. 22 is a top view of a modified first sensor of a sensor
assembly according to the present invention; and
[0050] FIG. 23 is a top view of a yet another variation of a first
sensor of a sensor assembly according to the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0051] Throughout all the Figures, same or corresponding elements
are generally indicated by same reference numerals. These depicted
embodiments are to be understood as illustrative of the invention
and not as limiting in any way. It should also be understood that
the drawings are not necessarily to scale and that the embodiments
are sometimes illustrated by graphic symbols, phantom lines,
diagrammatic representations and fragmentary views. In certain
instances, details which are not necessary for an understanding of
the present invention or which render other details difficult to
perceive may have been omitted.
[0052] FIGS. 1 to 23 depict various embodiments and details of a
sensor assembly according to the present invention for determining
a temperature state in the area of a heating surface 15 which has
been heated by a heat source 16 and may be a glass ceramic hot
plate for example. The sensor assembly is intended for use in
particular for glass ceramic areas of kitchen stoves and has
dimensions that can be suited to the application at hand. The
sensor assembly is positioned between the heat source 16 and the
heating surface in parallel relationship to the heating surface.
The heating surface 15 and the heat source 16 are shown in detail
in FIGS. 19 and 20.
[0053] FIGS. 1 to 3 show the basic principle of a sensor assembly
according to the present invention. The sensor assembly includes a
first sensor 1 arranged on a first carrier 26 and a second sensor 2
arranged on a second carrier 26'. Carrier 26 bears a resistor web
23. Likewise, carrier 26' also bears a resistor web of similar
construction which is, however, not shown in the drawings. The
resistor web 23 is in electrical contact with two of contact
elements 8 via rivets 6, contact pieces 5 and rivets 7. The
resistor web of sensor 2 provided on carrier 26' is in direct
contact with two of contact elements 8. In the particular
embodiment of FIGS. 1 to 3, the contact pieces 5 are S-shaped. The
sensor assembly further has a retention element 3 with a receptacle
4. For reasons of mounting, the sensor assembly has a mounting
bracket 9 with a hole 10.
[0054] FIGS. 4 to 6 show another embodiment of the present
invention. For sake of simplicity, identical and similar features
that have already be described with regard to FIGS. 1 to 3 will not
be explained again. For ease of illustration, the resistor web 23
actually provided on sensor 1 is not shown in FIGS. 4 to 20. It is
however to be understood that a temperature sensitive web has to be
provided for proper functioning of the sensor assembly. The
embodiment of FIGS. 4 to 6 differs from the one shown in FIGS. 1 to
3 in that the contact pieces 5 are Z-shaped. Hence, the first
sensor carrier 26 is longer and covers rivets 7 (see FIG. 6).
[0055] FIGS. 7 to 9 show yet another embodiment of the present
invention. Sensor 1 has two carrier parts 31 and 32. It therefore
has a recess 33 and a recessed zone 17.
[0056] FIGS. 10 to 12 show yet another embodiment of the present
invention. Sensor 1 has a single carrier 26. It also has a recess
33 and a recessed zone 17. However, recess 33 and recessed zone 17
form integral parts of the carrier 26.
[0057] FIGS. 13 and 14 show yet another embodiment of the present
invention. A spring tongue 11 is provided here between sensor 1 and
sensor 2. This tongue 11 urges sensor 1 upwards and hence--in
use--towards the heating surface 15. It therefore ensures proper
contact to the heating surface 15 which allows more accurate
temperature measurements. This embodiment includes a retention
element 3 isolating the sensor 1 from the heat source 16 (the
latter being shown in FIG. 20 but not in FIGS. 13 and 14).
[0058] FIGS. 15 to 17 show yet another embodiment of the present
invention. This embodiment is similar in structure than the
embodiment of FIGS. 13 and 14, with the difference residing in the
absence of the retention element. Therefore, this embodiment is
very simple in structure.
[0059] FIG. 18 shows a detail of yet another embodiment of the
present invention. In this embodiment a particular shape of the
retention element 3 is shown. The retention element 3 has grooves 1
forming reinforcement ribs having voids 14 therein. This particular
shape provides both enhanced stability and, due to the voids 14,
better insulating properties.
[0060] FIGS. 19 and 20 shows a sensor assembly according to the
present invention installed in an electric stove with a heating
surface 15 and a heat source 16.
[0061] FIGS. 21 to 23 show top views of different embodiments of
the first sensor 1 of a sensor assembly according to the invention.
In particular, different shapes of the carrier 26 are shown.
Although the different zones are only depicted in FIG. 21, each of
the three carriers of FIGS. 21 to 23 comprises, in principle, a
temperature measuring zone 28 with a resistor web 23 thereon, a
transition zone 29 and a contact zone 30 provided with contact
pieces 8. While the carrier 26 in FIG. 21 has a general rectilinear
shape, the carrier 26 in FIGS. 22 and 23 are of smaller diameter at
the distal end 34 of the carrier 26. In the embodiment of FIG. 22
the transition from the wider to the narrower carrier region is
realized by a step 35 while in the embodiment of FIG. 23 the
transition continues. Both arrangements reduce the weight of the
carrier 26 at the distal end 34. This in turn provides less
distortion and hence better stability and enhanced measuring
accuracy of the sensor.
[0062] The sensor assembly according to the present invention
essentially includes a first sensor 1 and at least one second
sensor 2. The sensor 1 has a carrier 26, which may be made of
ceramic, and at least one temperature-dependent resistor web 23,
which is shown by way of example in FIGS. 1 and 21 and arranged on
the carrier 26. The resistor web 23 is not shown in the other
figures for reasons of better comprehensibility of the drawings.
The resistor web 23 of the sensor 1 faces the heating surface 15
and is electrically contacted outside a temperature-measuring zone
28 of the sensor 1 to a contact zone 30 with contact pieces 8. The
sensor 2 has a carrier 26', which may be made of ceramic, and at
least one temperature-dependent resistor web (not shown but similar
to that on sensor 1), which is arranged on the carrier 26' of the
sensor 2 and faces the heat source 16 (FIG. 20). When assembled,
the sensor 1 rests as flatly as possible and directly upon an
underside of the heating surface 15.
[0063] As indicated in FIGS. 1 and 21, the resistor web 23 of the
sensor 1 and/or sensor 2 may have a meandering configuration and is
made preferably through thick-film technique. Any configuration of
meander shape may be possible. As a result of the meander shape,
the temperature-measuring zone 28 which is especially
temperature-sensitive can be defined. Although the meander shape is
currently preferred, any other configuration of the resistor web 23
is, of course, possible as well. While the application of
thick-film technique, using especially a screen printing process,
is currently preferred, thin-film technique or other processes at
the disposal of the artisan are, of course, also conceivable. The
sensors 1, 2 may be of substantially identical construction for
cost-saving reasons; currently preferred is however a configuration
in which the sensor 2 is made of greater size than the sensor 1 so
that the sensor 2 is able to shield the sensor 1 from heat
radiating from the heat source 16, as shown by way of example in
FIGS. 1 to 20. Shielding of the sensor 1 can further be enhanced by
making the sensor 2 radiation-absorbent.
[0064] The temperature measuring zone 28 can be further adjusted by
making the resistor web 23 of the sensor 1 and/or the resistor web
of the sensor 2 in a transition zone 29 between the contact zone 30
and the temperature-measuring zone 28 of a cross section 23a which
is greater than, in particular twice, a cross section in the
temperature-measuring zone 28. Greater cross section 23a means
smaller resistance and less temperature sensitivity which is
desired in the transition zone 29.
[0065] The stability of the sensor assembly can be enhanced by
tapering the sensor carrier 26 and/or 26' assembly in a direction
to a free end which is distal to the contact zone 30. As a result,
only a small portion of the heat source 16 is shielded from the
heating surface 15. In addition, this effect can be further
enhanced by providing the sensor assembly in the area of the
contact zone 30 with a wider portion 25 (FIGS. 22, 23), with a
transition from the wider portion 25 to the remaining narrower
portion 24 of the sensor assembly being curved, suitably concavely
curved.
[0066] Suitably, the resistor web 23 of the sensor 1 and/or sensor
2 has a length of at least 200 mm in the temperature-measuring zone
28 so as to be able to suit the temperature sensitivity. The
resistor web(s) 23 must be securely electrically contacted
consistently even when exposed to widely varying thermal
conditions. Suitably, the resistor web(s) 23 is contacted by at
least one contact piece 5 which is made of elastically yielding
material and connected, e.g. riveted, to the respective carrier. It
is also possible to insulate the resistor web(s) 23 by a closed
thermally conductive passivation layer (not shown) which, when
having sufficient width, is able to cover or screen any unevenness,
caused, e.g., by bolt heads and/or rivets 6, 7. As a result, the
sensor 1 rests flatly against the heating surface 15.
[0067] In view of the affect that the heat source 16 may have on
the sensor 1, the sensor 1 is isolated from the heat source 16 by
disposing a retention element 3 between the sensor 1 and sensor 2,
see FIGS. 1 to 14, 18 and 20. The retention element 3 may be
configured as a bracket or have a trough shape to define a
receptacle 4 for accommodating insulating material (not shown). The
retention element 3 may be made of any suitable thermally stable
material, e.g. ceramic or stainless steel. As shown in FIG. 18, the
retention element 3 has a bottom formed with grooves 13 to provide
reinforcement ribs with voids 14 for insulation.
[0068] FIGS. 13 and 14 show an embodiment of a sensor assembly,
having a spring tongue 11 for urging the sensor 1 against the
heating surface 15. The spring tongue 11 is connected to the sensor
2. In the sensor assembly of FIGS. 15, 16 and 17, the sensor 1 is
biased by a spring tongue 12 which is secured to the sensor 2. The
spring tongue 11, 12 may be a metal spring.
[0069] The sensor 2 is at least regionally connected to the
retention element 3 and bears flatly against the retention element
3.
[0070] The retention element 3 has preferably the shape of a
trapezoidal frame or the shape of a trough with trapezoidal or
rectangular configuration, with an underside and inner side of the
trough having preferably plane-parallel plates. As a result, the
sensors 1, 2 bear against the retention element 3. The receptacle 4
of the retention element 3 may be provided in either variation,
i.e. when the retention element 3 is configured as frame or as
trough.
[0071] As the sensor 1 should rest flatly upon the heating surface
15, the sensor 1, in particular the carrier 26 of the sensor 1, is
connected in the area of the contact zone 30 to the sensor 2 and/or
retention element 3. by at least one elastically yielding contact
piece 5, e.g. a spring such as a metal spring, U-shaped spring
(FIGS. 4-6, 7-9, 10-12, 13, 14, 15-17), or Z-shaped spring (FIGS.
1-3). To connect the elastically yielding contact piece 5 reliably
and consistently to the sensor 1, sensor 2, and/or retention
element 3, the use of thermally stable connection means are
provided, such as bolts and/or rivets 6, 7. Rivets in particular
are reliable, thermally stable, cheap, and allow automatic
installation.
[0072] When using rivets 6, 7 or bolts or like fasteners, the heads
of the fasteners 6, 7 jut out beyond the surface of the sensor 1 to
prevent a flat abutment of the sensor 1. While this may be
acceptable is some instances whereby the heads of the fasteners 6,
7 form a wedge-shaped gap, it is however preferred to implement a
flat abutment of the sensor 1 against the heating surface 15. This
may be attained by applying a thermally conducting passivation
layer upon the surface of the sensor 1, with the passivation layer
covering also the heads of the fasteners 6, 7. As an alternative,
or in addition, the sensor 1 is formed in the area of the contact
zone 30 with a step-shaped recessed zone 17 which extends at a
lower level as the thermally stable connection means, as shown in
FIGS. 7 and 9. When the sensor 1 is completely received in the
receptacle 4 of the retention element 3, the resistor web 23 of the
sensor 1 extends in substantial parallel relationship to the sensor
2. The step-shaped recessed zone results in a flat abutment of the
sensor 1 upon the heating surface 15 in the absence of any
interference by the heads of the fasteners 6, 7.
[0073] Suitably, the carrier of the sensor 1 is of multipart
configuration in the area of the recessed zone 17. In this way, the
part that is relevant for the measurement, i.e. the part of the
carrier 26 with the measuring zone 28, can be configured as a flat
part that can be connected to a further part to form a step, as
shown in FIGS. 7 and 9.
[0074] In the embodiment shown in FIGS. 7 to 9, the sensor 1 is
made up of two carrier parts 31 and 32. By arranging the two
carrier parts 31 and 32 as shown in FIGS. 7 and 8 a recess 33 and
hence recessed zone 17 is formed.
[0075] FIGS. 10 to 12 show an alternative to form the recess 33 and
hence a recessed zone 17. As shown in FIGS. 10 and 12, the sensor 1
has a single piece carrier 26. The recess 33 is already an integral
part of the carrier 26 and can be applied by grinding or other
abrasive treatment of the carrier 26.
[0076] With regard to FIGS. 1 to 20, installation and adjustment in
a heating space formed by the heat source 16 and the heating
surface 15 is realized by using a mounting bracket 9 of
substantially angular shape. The mounting bracket 9 is connected to
the sensor 2 and/or the retention element 3, e.g. by riveting ort
bolting. When connected to the retention element 3, the mounting
bracket 9 can have a pocket or bay (not shown) for receiving the
sensor 2. This allows easy installation of the sensor 2. The
mounting bracket 9 has a vertical oblong hole 10 to facilitate
assembly and adjustment.
[0077] While the invention has been illustrated and described in
connection with currently preferred embodiments shown and described
in detail, it is not intended to be limited to the details shown
since various modifications and structural changes may be made
without departing in any way from the spirit of the present
invention. The embodiments were chosen and described in order to
best explain the principles of the invention and practical
application to thereby enable a person skilled in the art to best
utilize the invention and various embodiments with various
modifications as are suited to the particular use contemplated.
* * * * *